Ruf Thomas, Bieber Claudia
Research Institute of Wildlife Ecology, Department of Interdisciplinary Life Sciences, University of Veterinary Medicine, Vienna, Austria.
Front Physiol. 2020 May 5;11:423. doi: 10.3389/fphys.2020.00423. eCollection 2020.
The edible dormouse (, formerly ) is a small arboreal mammal inhabiting deciduous forests in Europe. This rodent shows behavioral and physiological adaptations to three types of environmental fluctuations: (i) predictable seasonal variation in climate and food resources (ii) unpredictable year-to-year fluctuation in seed-production by trees and (iii) day-to-day variation in ambient temperature and precipitation. They cope with seasonally fluctuating conditions by seasonal fattening and hibernation. Dormice have adjusted to tree-mast fluctuations, i.e., pulsed resources, by sensing future seed availability in spring, and restricting reproduction to years with at least some seed production by beech and oak trees, which are a crucial food-resource for fast-growing juveniles in fall. Finally, dormice respond to short-term drops in ambient temperature by increased use of daily torpor as well as by huddling in groups of up to 24 conspecifics. These responses to environmental fluctuations strongly interact with each other: Dormice are much more prone to using daily torpor and huddling in non-reproductive years, because active gonads can counteract torpor and energy requirements for reproduction may prevent the sharing of food resources associated with huddling. Accordingly, foraging activity in fall is much more intense in reproductive mast years. Also, depending on their energy reserves, dormice may retreat to underground burrows in the summers of non-reproductive years, causing an extension of the hibernation season to up to 11.4 months. In addition to these interactions, responses to environmental fluctuations are modulated by the progression of life-history stages. With increasing age and diminishing chances of future reproduction, females reproduce with increasing frequency even under suboptimal environmental conditions. Simultaneously, older dormice shorten the hibernation season and phase-advance the emergence from hibernation in spring, apparently to occupy good breeding territories early, despite increased predation risk above ground. All of the above adaptions, i.e., huddling, torpor, hibernation, and reproduction skipping do not merely optimize energy-budgets but also help to balance individual predation risk against reproductive success, which adds another layer of complexity to the ability to make flexible adjustments in this species.
食用睡鼠（学名：，曾用名：）是一种小型树栖哺乳动物，栖息于欧洲的落叶林中。这种啮齿动物在行为和生理上适应了三种环境波动类型：（i）气候和食物资源可预测的季节性变化；（ii）树木种子产量不可预测的逐年波动；（iii）环境温度和降水量的每日变化。它们通过季节性育肥和冬眠来应对季节性波动的条件。睡鼠通过感知春季未来的种子可获得性，并将繁殖限制在山毛榉和橡树至少有一定种子产量的年份，从而适应了树木结实的波动，即脉冲式资源，山毛榉和橡树是秋季快速生长的幼崽的关键食物资源。最后，睡鼠通过增加每日蛰伏的使用以及聚集在多达24只同种个体的群体中来应对环境温度的短期下降。这些对环境波动的反应相互之间有强烈的相互作用：睡鼠在非繁殖年份更倾向于使用每日蛰伏和聚集，因为活跃的性腺会抵消蛰伏，而繁殖所需的能量需求可能会阻止与聚集相关的食物资源共享。因此，在繁殖丰年的秋季，觅食活动更为强烈。此外，根据它们的能量储备，睡鼠可能在非繁殖年份的夏季退回到地下洞穴，使冬眠季节延长至11.4个月。除了这些相互作用外，对环境波动的反应还受到生命史阶段进展的调节。随着年龄的增长和未来繁殖机会的减少，雌性即使在次优环境条件下也会更频繁地繁殖。同时，年龄较大的睡鼠会缩短冬眠季节，并提前在春季从冬眠中苏醒，显然是为了尽早占据良好的繁殖领地，尽管地面上的捕食风险增加。上述所有适应方式，即聚集、蛰伏、冬眠和繁殖跳过，不仅优化了能量预算，还有助于平衡个体的捕食风险与繁殖成功率，这为该物种进行灵活调整的能力增加了另一层复杂性。
